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theano/tensor/basic.py

@@ -1413,6 +1413,14 @@ class _tensor_py_operators:
         return cast(self, dtype)
 
     #SLICING
+    # Do not define __getslice__ here:
+    # When calling t[1:], for instance, the arguments passed to __getslice__
+    # are (1, sys.maxsize), which is a pain to deal with, and can even not be
+    # an int (but a long).
+    # If __getslice__ does not exist, __getitem__ is called instead, with
+    # argument slice(1, None, None), which is much more desirable.
+    # __getslice__ is deprecated in python 2.6 anyway.
+
     def __getitem__(self, args):
         if not isinstance(args, tuple):
             args = args,
@@ -3117,6 +3125,9 @@ def get_canonical_form_slice(theslice, length):
                            , switch(lt(step,0),length-1,length)
                            , start)
         if stop in [None, sys.maxsize]:
+            # The special "maxsize" case is probably not needed here,
+            # as slices containing maxsize are not generated by
+            # __getslice__ anymore.
             stop = defstop
         else:
             stop = switch(lt(stop,0), stop + length, stop)
@@ -3239,6 +3250,9 @@ class Subtensor(Op):
                 slice_a = None
 
             if b is not None and b != sys.maxsize:
+                # The special "maxsize" case is probably not needed here,
+                # as slices containing maxsize are not generated by
+                # __getslice__ anymore.
                 slice_b = Subtensor.convert(b, False)
             else:
                 slice_b = None